Q6

[soyeonjeon]

I am really lost on this one. They all seem correct. Especially A and B. why are they wrong?
Isn't 6PM the only hour on which Gabriel's audition cannot begin? wherein, Gabriel's audition is scheduled to begin before 5 pm?
Or Am I misinterpreting before? Does before 5 pm mean 1, 2, 3, 4 but not 5pm?

If so, shouldn't C be the correct answer and not E?

Please help me out. Thanks.

[ohthatpatrick]

Let's try to create counterexamples for all the wrong answer choices, since that's the best way to prove an answer choice is wrong on must be true.

(A) I would test "Can G be 5?"
F J H L G K
If G can be 5pm, then it doesn't HAVE to be true that G is before 5pm.

(B) I would test "Can H be 2?"
J H L G K F

(C) I would test "can H be 6"?
J F L G K H

(D) I would test "can K be 6?"
F J H L G K

(E) I would test "can L be 5?"
Here, I hit a brick wall.

If L is 5, then K is 6
so L K are my last two.
G has to be attached to L, so G L K are my last three.
J has to be one away from L, so J G L K are my last four.

But H has to come after J ... I'm stuck!

Since there's no counterexample, L must be before 5.

"Before 5" means the only possible options are 1, 2, 3, 4.

Counterexamples would be 5 or 6. (L can never be 6, because K has to come after the GL chunk)

This was a tough question, since almost no one would have the correct answer as part of his/her original deductions. Hopefully, your previous work allows you to knock out a couple answer choices, but then we might have to just plug-n-chug the last few to see which ones can't be refuted.

Let me know if confusion remains.

[KatiaK713]

Hi there,
Is there a faster way here than trying all the answers?

[ohthatpatrick]

In general, do your "IF" questions before you do any of these unconditional ones.
(Here, that advice is unimportant, since this is the last question.)

When you start an unconditional question, try to eliminate answers based on previous work.

For a MUST BE TRUE question, you can eliminate any answer choice for which you have a counterexample. So go looking for counterexamples.

(A) Can G ever be 5 or 6?
(B) Can H be 2 or 1?
(C) Can H be 6?
(D) Can K be 6?
(E) Can L be 5 or 6?

Normally, if you look around your previous work, you've already seen at least a couple of those are possible.

Otherwise, get testing.
(A) can G be 5 or 6?
Definitely not last because of the (GL) - K rule, but 5 seems doable. Let's investigate
__ __ __ L G K

That would determine J, which determines H, which leaves F.
F J H L G K

Eliminate (A). Also eliminate (D), since we just proved that K can be 6.

(B) Can H be 2 or 1? It can't be 1, because of J - H, but it could probably be 2. Test it.
_ H _ _ _ _

This determines J, which determines, L, which determines G
J H L G (F, K)

Eliminate (B).

(C) Can H be 6? Probably. I'd start with this, even though J doesn't NEED to be 5.
__ __ __ __ J H

That determines L, which determines K and then G, which leaves F at 1.
F G L K J H

Eliminate (C).

Pick (E).

Some people, when taking that first pass through the answers will see the problem created with trying to avoid (E)
(E) could L be 5 or 6?

It couldn't be 6 because of (GL) - K
It looks like it could be 5.
But putting L in 5, means G is in 4, and J is in 3, and that leaves no room for H.

If we don't see those chain reactions, then we should just get writing!